The overall aim of this Phase I proposal is to devise therapeutic modalities which will assure constitutive expression of antigenic proteins needed for effective cell-mediated immunity against the tumor cells. These studies will focus on the regulation of genes that modulate the expression of the melanocyte lineage antigen, Melan-A/MART-1. We shall elucidate the mechanisms by which recently characterized tumor-produced cytokines effect "antigen silencing." We shall perform a detailed analysis of mechanisms for transcriptional control of Melan-A/MART-1 as a means to overcome suppression of Melan-A/MART-l expression. Candidate transcription factors will be tested to determine if they bind to the Melan-A/MART-1 promoter. Occupancy of the Melan-A/MART-1 promoter will also be assessed by DNA footprinting. A series of Melan-A/MART-1 promoter reporter constructs will be used to analyze putative transcriptional repression sites in the promoter region. These studies will compare Melan-A/MART-1 positive and negative tumor cell variants, as well as assess the effects of antigen-silencing cytokines on mRNA transcripts and promoter occupancy. The results of this Phase I project will allow us to devise strategies for enhancement of Melan-A/MART-1 expression to overcome "antigen-silencing."